1. Field of the Invention
The invention relates to a device for treatment of a substrate with which different substrates, such as for example, semiconductor devices, printed boards, LCD substrates or the like can be treated. The invention, furthermore, relates to a device for treatment of a substrate in which, after removing a workpiece from a cassette by a workpiece transport device and after a first treatment, such as for example rough alignment or the like, a second treatment, for example, exposure or the like, is performed, and the already treated workpiece is automatically transported to the cassette.
2. Description of Related Art
In a device for working and treatment of a workpiece, such as a semiconductor wafer or the like, transporting the workpiece using a robot as the transport device, which is shown, for example, in published Japanese patent application HEI 8-274140, is known.
In one such robot, a device is used in which dust formation when driving is suppressed as much as possible. It is used in a process in which there is a demand for high cleanliness.
FIG. 14 shows one example of the above described robot.
In the figure, a robot RA has a rotary part RA 20 which is pivotally supported on a base RA10, first arms RA3, RA3' which turn on the rotary part RA20, second arms RA5, RA5' which are pivotally installed on the first joints RA4, RA4' in the first arms RA3, RA3', and workpiece holding arms RA1, RA1' which are pivotally installed on the second joints RA6, RA6' in the second arms RA5, RA5'. On the tips of the workpiece holding arms RA1, RA1' which are located at the top and bottom, there are workpiece holding parts RA7, RA7' which securely hold a workpiece by vacuum Suction or the like.
In the second arms RA5, RA5', there are recess components RA8, RA8' for preventing mutual interference of the arms which are attached in the workpiece holding arms RA1, RA1'. The workpiece holding arms RA1, RA1' are pivotally installed in the second alms RA5, RA5' via the recess components RA8, RAS8'.
The workpiece holding arms RA1, RA1' each move independently of one another in the same direction (in the direction of the arrows in the drawings), the axis b of the rotary part RA2 acting as the zero point. Turning the rotary part RA20 changes the direction of the workpiece holding arms RA1, RA1'. This means that the workpiece is held securely by the two holding alms RA1 and RA1' which are located at the top and bottom. The workpiece is transported by the rotary motion.
However, in the arrangement of one Such robot, as the transport device, there are the following defects:
(1) As is shown in FIG. 14, the arms are extended or retracted. Therefore, the arms have a multi-jointed arrangement. Thus, the joints of the arms project above the robot rotary part. As a result, when the robot turns for transporting,g of the workpiece, it is necessary to ensure space for rotation so that no interference occurs between the arms, the workpiece which is held by the arms, and the other parts of the device. The cage-like body of the device therefore becomes large. PA1 (2) The total height of the robot becomes large due to the arrangement of the joints and by the two arms being located at the top and bottom. PA1 (1) As is shown in FIG. 16(a), the first arm RA1 is extended in the direction toward the first cassette receiving part CS1 and holds n-th workpiece Wn of cassette 1. The first arm RA1 is retracted and the workpiece Wn is removed. PA1 (2) The workpiece transport device RA turns in the direction to the alignment part FA. The first al RA1 is extended. The workpiece Wn is placed on the alignment part FA. Then, the arm RA1 is retracted. PA1 (3) The workpiece transport device RA turns in the direction toward the exposure part WS. As is shown in FIG. 16(c), the second arm RA1' is extended, receives the already exposed n-1-th workpiece Wn-1 from the exposure part WS and is retracted. The first arm RA1 is extended, the workpiece Wn is seated on the exposure part WS and is retracted. PA1 (4) In the exposure part WS, the workpiece Wn is exposed. In the meantime, the workpiece transport device RA turns in the direction toward the second cassette receiving part CS2. As is shown in FIG. 16(d), the second arm RA1' is extended, receives the workpiece Wn-1 into the cassette 2 in the second cassette receiving part CS2, and is retracted. PA1 (5) As is shown in FIG. 16(e), the workpiece transport device RA turns in the direction toward the first cassette receiving part CS1. PA1 (6) The first arm RA1 is extended and removes the n+1-the workpiece Wn+1 of the cassette 1 of the first cassette receiving part CS1. Afterwards processes (1) to (5) are repeated. PA1 Since a workpiece transport device with a multi-jointed arrangement which has a rotary device is used, it was necessary to ensure a space for rotation so that there is no interference between the arms, the workpiece which is held by the arms, and the other parts of the device. PA1 Since the total height of the robot is great, the cage-like body of the device is large. PA1 The waiting time in the treatment parts and the workpiece replacement time were long. Therefore, the throughput could not be increased. PA1 several cassette receiving parts, each of which has a cassette in which a respective workpiece is seated; PA1 a first treatment part in which, with respect to the seated workpiece, a first treatment takes place; PA1 a second treatment part in which, with respect to the seated workpiece, a second treatment takes place which follows the first treatment, and PA1 workpiece transport devices, as follows:
Therefore, it is difficult to remove the robots in the transverse direction of the cage-like body in which the robots, machining parts and the like are located. With consideration of the removal of the robot from the device, while waiting, there must be a waiting space above the robot, causing the entire device to become large.
If the robot can be removed in the transverse direction of the device, it is certainly not necessary to arrange the waiting space at the top. Since the overall height of the robot is however great, an arrangement must be made in which some of the frame of the cage-like body is absent in order to remove it in the transverse direction. In this way, however, the strength of the device is reduced, so that it cannot be done.
In one such device, on the other hand, there is a requirement for increasing the number of workpieces which can be treated within a unit of time, i.e., the throughput, as much as possible.
To improve the throughput, it is important to shorten the waiting time of the treatment parts of the device as much as possible. The expression "waiting time of the treatment parts of the device" is defined as the time after completion of treatments of the workpiece by the treatment parts until starting of treatments of the next workpiece. This time includes the time in which it is awaited for the next workpiece to be transported to the treatment part and the time in which the transported next workpiece (before treatment) is exchanged for the already treated workpiece.
To shorten the waiting time of the treatment part, it is necessary to transport the workpiece with high efficiency; this takes place as follows: Removal from the housing (cassette), in which the workpiece is located.fwdarw.Transport to the treatment part.fwdarw.reception of the already treated workpiece into the housing (cassette)
In the following, using the substrate treatment device which is shown, by way of example, in FIG. 15, the throughput for movement and treatment of the workpiece using the above described workpiece transport device is described.
In the substrate treatment device which is shown in FIG. 15, there are cassette receiving carriers CS1, CS2 (hereinafter called "cassette receiving parts") on each of which a respective housing (hereinafter called "cassette") is seated in which the workpiece is located, an alignment part FA (a first treatment part) and an exposure part WS (a second treatment part) for exposure around the circular periphery of the rotating workpiece carrier device RA.
In the above described alignment part FA, positioning is performed in order to scat the workpiece in a stipulated position of the exposure part WS. In the exposure part WS, exposure light is emitted onto the workpiece which is seated on the exposure part via a mask on which a mask pattern is formed. Thus, the mask pattern is transported to the workpiece.
The workpiece transport device RA, on its end, has plug-in workpiece holding arms RA1, RA1' which are provided with vacuum suction grooves as shown in FIG. 14.
By extending or retracting the arms RA1, RA1', the workpiece is removed from the respective site or is seated on the respective site. The workpiece which is fixed on the arms RA1, RA1' is transported by rotary motion of the workpiece transport device RA from one site to another.
The two arms RA1 and RA1' of the workpiece transport device RA are located at the top and bottom, as is shown in FIG. 14. The workpiece can be exchanged before treatment for the already treated workpiece by the two arms RA1, RA1' in the treatment parts FA, WS.
In the following, the sequence of workpiece transport in the case of using the workpiece transport device in FIG. 14 is described for the substrate treatment device in FIG. 15:
In this case, for example, processes are imagined in which the workpiece W is removed from a cassette 1 which is located in the first cassette receiving part CS1 and after treatment is received into a cassette 2 which is located in the second cassette receiving part CS2, as is shown in FIGS. 16(a) and 16(b).
Alignment is performed in the alignment part FA. After completion of alignment, the first arm RA1 is extended, as is shown in FIG. 16(b), receives the workpiece Wn from the alignment part FA, and is retracted.
The movement and treatment of the workpiece in the above described substrate treatment device is shown in FIG. 17, in which the x-axis plots the time and the y-axis plots the position at which the workpiece is located. The respective line represents the behavior of the workpiece flow, and the squares show that the respective treatment is being performed.
In the figure, the duration of alignment in the alignment part FA was 5 seconds and the duration of exposure in the exposure part WS was 15 seconds. Furthermore, the time in which the arms are extended, the time in which the arms are retracted, the time in which the workpiece is transferred from the arms to the respective part, and the time in which the workpiece is transferred from the respective site to the arms were each 1 second and the time in which the workpiece transport device turns is 2 seconds.
In the substrate treatment device in FIG. 15, when the workpiece in the exposure part WS is exchanged, the arms of the workpiece transport device RA must perform six movement steps, specifically, the extension of the first arm RA1, the transfer of the workpiece by the first arm RA1, retraction of the first arm RA1, the extension of the second arm RA1', transfer of the workpiece by the second arm RA1' and retraction of the second arm RA1'. The exchange time is therefore 6 .times.1 seconds, i.e., 6 seconds.
Even when the exposure of the workpiece in the exposure part WS is completed, the alignment of the next workpiece is not yet ended. Therefore, the waiting time for the next workpiece is 10 seconds.
The time from starting of the treatment of the n-th workpiece Wn until starting of the treatment of the n+1-th workpiece Wn+1 in the exposure part WS, i.e., the cycle time, therefore, is 31 seconds, as is shown in FIG. 17.
In a conventional substrate treatment device, the defects were the following: